In a postmortem chat with THR following "Mad Love," the actress says, "Every agent on this case has to face a choice at one point or another in terms of how much danger they’re willing to take on."

[Warning: Spoilers from Monday's "Mad Love" and beyond.]

It's Joe Carroll vs. the world.

In the latest episode of Fox's thriller The Following, "Mad Love," one of Joe Carroll's (James Purefoy) dangerous followers, Maggie (Virginia Kull), devises a plan to end Ryan Hardy (Kevin Bacon) once and for all. This continues the FBI's desperate search to reunite Claire Matthews (Natalie Zea) with her kidnapped son, Joey (Kyle Catlett). And though Maggie's quest to end Ryan comes up short, Annie Parisse, who plays FBI Specialist Debra Parker -- a cult expert -- hints that there's much more danger headed the team's way.

"[In] episode five and six, there’s a big shakeup," Parisse tells The Hollywood Reporter, adding that "there’s another big shakeup around episode 10 where you really think the show is going in one direction, then it takes a dramatic left turn."

Parisse talked to THR following Monday's episode -- which included another twist on the Jacob, Paul and Emma follower arc -- about whether the tide will shift against Joe, whether Parker will be faced with a life-altering decision and when viewers will learn more about her mysterious, dark past.

The Hollywood Reporter: At this point, we don’t know Debra Parker’s full back-story or how she’ll be more deeply ingrained in the mystery. How does her knowledge of cults play into this?

Annie Parisse: Parker has a wealth of experience with cults and a wealth of knowledge about them. Ultimately, her knowledge about that field is brought to bear on the case and on finding Joey – and certainly, in the end, this particular case impacts her in a way other cases haven’t. We saw a little bit in last week’s episode that she comes from an academic place. This experience with Joe’s cult is going to affect her personally in a profound way, starting with Reilly’s (Billy Brown) death, because it was so close to the bone and she’s never experienced that before. Those types of events will keep happening.

THR: Was Reilly's death an indication that this is a whole other beast they’re dealing with? What’s her outlook on the situation?

Parisse: Where Parker is at the end of [episode] 103 is really a new place, that she was fooled by Maggie. She earnestly believed that Maggie was the victim of domestic abuse, and she was somebody who was taken in by a member of this horrible cult, and Parker felt the need to protect her. In the end, it’s humiliating to be taken in. Number one, that's not an experience she’s used to, and number two, she doesn’t have as much of a grasp over what might be happening with Carroll’s cult as she originally thought, which is scary.

THR: What is it about this particular case that stands out for her?

Parisse: It’s like a scientist discovering a new species. It’s rare to discover new alternative religions, new cults and to get to witness, observe, work with them, and this is on the absolute edge. Part of it for her is a scientific interest; these people are completely fascinating, and there is a part of her – especially in the beginning – that is relishing the opportunity to look through the window into this crazy, crazy world. The only other example she would be familiar with would be Charles Manson.

THR: There sounds like there’s some respect from Parker for what Joe has pulled off.

Parisse: Yeah, absolutely! This thing he’s set up is unbelievable. It’s masterful. I go back to a scientist who’s looking at the most insane, giant arachnid, and all of us on the outside are like, “Oh my god, that’s disgusting!” and the entomologist is like, “But look at how beautiful!” It becomes so real and so close to home that all of that fear and anger takes over. Carroll is toying with everybody, and that becomes clear.

THR: After the fourth episode, it's clear Joe Carroll is always one step ahead of everyone else. Does Parker come up with different ways to get ahead?

Parisse: I think it feels like the team is really struggling to catch up, that they’re really racing to catch him, because he has such a big head start. There are a couple of big moments coming where the tide really turns. And then the tide turns back again. It’s really tricky.

THR: Does the working relationship between Ryan and Parker evolve in a significant way?

Parisse: Ryan and Parker get closer and closer as the season goes on. What you find out as the episodes unfold is that Parker has a pretty dark past as well, and they’re kind of similarly damaged and similarly isolated in the world. They really understand one another, or Parker is able to understand Ryan, [something] he hasn’t gotten professionally in the past.

THR: Will they start seeing eye-to-eye?

Parisse: Tactically, they’re pretty different, in terms of core life journeys, core understandings. Ryan’s initial impulse is a lot more impulsive than Parker’s is. She’s more of a thinker. There’s continued conflict there.

THR: How does Mike Weston (Shawn Ashmore) play into this? We know he’ll have to make a big personal sacrifice down the line for the sake of the case.

Parisse: Parker is protective of Weston. She sees so much potential in him. He’s a young guy who’s made it really far, really fast. There’s a level of concern there in regards to his relationship with Ryan. Every person who works on this case, in every episode, it was made clear in last week’s episode with Agent Reilly dying that there’s that real risk. There is no false jeopardy. Every character is genuinely at risk, and that certainly goes for Weston.

THR: This week’s episode saw Ryan going to great lengths -- nearly dying -- to save those he loves. In this case, his sister. Will Parker be presented with a similar situation?

Parisse: Yes. Every agent on this case has to face a choice at one point or another in terms of how much danger they’re willing to take on, and every character, I would say, goes farther than they’re comfortable with. Every character puts themselves into positions that are terrifying for them personally.

THR: Viewers have speculated that Parker’s dark past ties into her immense knowledge of cults, and maybe even that she was a part of one. Is that an accurate reading?

Parisse: People have said a ton of things to me about [Parker], and what’s exciting about all that [is] it shows how well Kevin Williamson has set everybody up in the beginning to feel off-balance, so the audience really feels like they don’t know who they can trust. The audience is right to be suspicious. No character on this show is without complications or secrets.

THR: What’s the craziest theory someone's told you?

Parisse: The one that stood out to me was somebody actually asked if Weston was a follower of Ryan Hardy, that he seemed like he would be in a Ryan Hardy cult. [Laughs] I thought that was really funny.

THR: One scene that was a topic of conversation happened a few episodes back, when Parker gave Joe reading material. That introduced a flurry of theories that there could be something deeper going on.

Parisse: I definitely had a lot of questions about that scene. What’s funny is that if you were to ask me that before the episode had aired, I never would have thought, “Oh! Look out for this scene coming up,” because when we shot it, it was just a brief scene. I was surprised by how everybody reacted to it, and I don’t think I would have necessarily predicted that.

THR: What's coming up for Parker?

Parisse: In the next three or four episodes, you’re going to get to know a lot about Parker’s past and why she does what she does. You’re going to get to know a lot of people in her past. You’re going to have a clearer sense of who she is and why she’s on this case.